I am soliciting opinions on something.

I have a small server maintaining about 300 filesystems in 30TB on one client 
running Linux.  I
have a very fast (dual Xeon with 4GB memory) Linux server running with a very 
fast Linux client
(single 3GHz class machine) all on a private gigE network.  Once things 
stabilize, I figure about
250-500GB per evening will be backed up, eventually to LTO1 by way of the disk 
storage pool(s)..

I have the following storage pools:

DISK - 250GB local 15K RPM disk
SLOW - 1TB+ NFS-mounted over gigE
TAPE - LTO1 drives

Currently, I'm testing backing up to the fast disk and having the slow disk as 
the next storage
pool and then finally to the tape.  The NFS mounted disk runs at about 35-50% 
of the speed of the
local disk (when comparing backup time and migration time).

The SLOW pool is basically free surplus equipment.  The local fast DISK pool is 
expensive and
scarce.  The TAPE drives are just generic manual LTO drives.

The SLOW pool is being leveraged for its cache value (pun intended) and I'm 
trying to use it to
have the maximum number of recent file backups present online (as opposed to 
only 250GB online
using the fast disk).

Assuming that there are no bottlenecks (backups feed the fast DISK storage pool 
and it's able to
feed the SLOW pool before it fills up), is this a sane architecture?  As Wanda 
and others
mention, the server and client are spending a great deal of time doing database 
transacations so
I don't think the data stream is going to overwhelm any of these storage pools.